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71.
F. Lorenzo A. Alonso M. J. Pellicer J. L. Pagés M. Pérez-Arlucea 《Environmental Geology》2007,52(4):789-802
This research focuses on the development of metal pollution in sediment cores from three estuaries in Northwest Spain: Viveiro,
Ortigueira and Barqueiro. Pb, Cu, Co, Cr, Cd and Zn and total organic carbon were assessed using principal component analysis
(PCA) in order to obtain background values, measure pollution levels and identify pollution sources. Results were interpreted
by considering the local industrial history, grain size and C/N relationship. The pollution levels obtained bear a strong
resemblance to those documented for of a moderately industrialised area. PCA identifies factors that reflect mainly temporal
associations with metals. Sedimentation rates between 0.9 and 1.1 cm/year were determined. In Viveiro core levels of Cr pollution
are associated with tanneries. In Ortigueira, high core levels of Cu and Co are linked to mining, and Cr levels to adjacent
ultramafic rocks. Erosion of Holocene sediment causes high values of Co and Cr in the Barqueiro core. Cu increase in the three
estuaries is related to fungicide use since 1910. Sea level rise appears to be affecting the marine characteristics of the
sediments in Barqueiro. In Viveiro, the nature of the sediment reflects engineering work and land reclamation. 相似文献
72.
Watershed management and headwater reconstruction programs require a reliable knowledge of sediment dynamics. Geographical Information Systems (GIS) provide the framework for the implementation of different complex techniques for the assessment of shallow landsliding and erosion processes in mountain basins. This paper presents some morphometric indicators aimed at erosion and sediment delivery analysis. The proposed indicators can be easily derived from medium to fine resolution Digital Elevation Models (DEM). Applications conducted in Eastern Italian Alps have shown the adequateness of the proposed approach to address erosion and sediment-related problems. The analysis considered the classification of sediment source areas with regard to their activity, the comparison between drainage basins having different morphological characteristics and the topographic control on sediment transport capacity, with a particular attention to the identification of channel reaches characterised by a low sediment transport capacity. 相似文献
73.
Salvatore de Lorenzo Elisabetta Giampiccolo Carmen Martinez-Arevalo Domenico Patanè Annalisa Romeo 《Journal of Volcanology and Geothermal Research》2010,189(3-4):247-256
A crucial point in the analysis of tectonic earthquakes occurring in a volcanic area is the inference of the orientation of the structures along which the ruptures occur. These structures represent zones of weakness which could favor the migration of melt toward the surface and the assessment of their geometry is a fundamental step toward efficient evaluation of volcanic risk. We analyzed a high-quality dataset of 171 low-magnitude, tectonic earthquakes that occurred at Mt. Etna during the 2002–2003 eruption. We applied a recently developed technique aimed at inferring the source parameters (source size, dip and strike fault) and the intrinsic quality factor Qp of P waves from the inversion of rise times. The technique is based on numerically calibrated relationships among the rise time of first P waves and the source parameters for a circular crack rupturing at a constant velocity. For the most of the events the directivity source effect did not allow us to constrain the fault plane orientation. For a subset of 45 events with well constrained focal mechanisms we were able to constrain the “true” fault plane orientation. The level of resolution of the fault planes was assessed through a non linear analysis based on the random deviates technique. The significance of the retrieved fault plane solutions and the fit of the assumed source model to data were assessed through a χ-square test. Most of the retrieved fault plane solutions agree with the geometrical trend of known surface faults. The inferred source parameters and Qp are in agreement with the results of previous studies. 相似文献
74.
Lorenzo Picco Luca Mao Riccardo Rainato Mario A. Lenzi 《Geografiska Annaler: Series A, Physical Geography》2014,96(1):83-97
River islands are defined as discrete areas of woodland vegetation surrounded by either water‐filled channels or exposed gravel. They exhibit some stability and are not submerged during bank‐full flows. The aim of the study is to analyze the dynamics of established, building, and pioneer islands in a 30‐km‐long reach of the gravel‐bed Piave River, which has suffered from intense and multiple human impacts. Plan‐form changes of river features since 1960 were analyzed using aerial photographs, and a LiDAR was used to derive the maximum, minimum and mean elevation of island surfaces, and maximum and mean height of their vegetation. The results suggest that established islands lie at a higher elevation than building and pioneer islands, and have a thicker layer of fine sediments deposited on their surface after big floods. After the exceptional flood in 1966 (RI > 200 years) there was a moderate increase in island numbers and extension, followed by a further increase from 1991, due to a succession of flood events in 1993 and 2002 with RI > 10 years, as well as a change in the human management relating to the control of gravel‐mining activities. The narrowing trend (1960–1999) of the morphological plan form certainly enhanced the chance of islands becoming established and this explains the reduction of the active channel, the increase in established islands and reduction of pioneer islands. 相似文献
75.
76.
Mauro Coltorti Andrea Brogi Lorenzo Fabbrini Dario Firuzabadì Lapo Pieranni 《Natural Hazards》2011,59(1):191-208
The eastern side of the Mt. Amiata volcano is affected by a series of deep-seated gravitational slope deformations (DsGSDs).
The San Piero and the Podere Mezzavia DsGSDs affect the lower part of the slope. The main escarpments are located on the outer
edges of the lava flows, but the landslides mostly affect the pre-volcanic Ligurian Terrains. A deeper movement, possibly
exceeding 100 m in thickness, is evidenced by a long trench at the base of the main escarpment that indicates a sagging type
movement. This deeper movement is responsible for the activation of a series of superficial rock and mud flows that show evidence
of ongoing activity. The most likely location of the sliding surface is the tectonized contact between the Santa Fiora and
Argille a Palombini Fms within the Ligurian units, although the superficial landslides prevent our determining with certainty
if a clear-cut sliding surface already developed connecting the upper and the lower parts of the slope. These DsGSDs were
activated along the flanks of a larger movement that affects the lava flow units cropping out in the middle slope of the volcano.
A long main escarpment, secondary escarpments, trenches and borehole data suggest that the thickness could locally exceed
200 m and generate another sagging type movement. Up-slope and up-movement-facing counterscarps indicate the existence of
a listric elongated spoon-shaped compound embryonic sliding surface. This sagging, which hosts the towns of Abbadia San Salvatore
and Piancastagnaio, appears to be in a quiescent stage, according to preliminary monitoring with a global positioning system
(GPS) network. The downcutting of the river network along the softer Pliocene terrains of the Radicofani basin is enhanced
by the general uplift of the Apennines and seems to be the major factor in the activation of these DsGSDs. 相似文献
77.
Tiziano Boschetti Lorenzo Toscani Orfan Shouakar-Stash Paola Iacumin Giampiero Venturelli Claudio Mucchino Shaun K. Frape 《Aquatic Geochemistry》2011,17(1):71-108
The salt waters from the Emilia-Romagna sector of the Northern Apennine Foredeep have been investigated using major and trace
element and stable isotope (δ2H, δ18O, δ37Cl, δ81Br and 87Sr/86Sr ratio). Ca, Mg, Na, K, Sr, Li, B, I, Br and SO4 vs. Cl diagrams suggest the subaerial evaporation of seawater beyond gypsum and before halite precipitation as primary process
to explain the brine’s salinity, whereas saline to brackish waters were formed by mixing of evaporated seawater and water
of meteoric origin. A diagenetic end-member may be a third component for mud volcanoes and some brackish waters. Salinization
by dissolution of (Triassic) evaporites has been detected only in samples from the Tuscan side of the Apennines and/or interacting
with the Tuscan Nappe. In comparison with the seawater evaporation path, Ca–Sr enrichment and Na–K–Mg depletion of the foredeep
waters reveal the presence of secondary processes such as dolomitization–chloritization, zeolitization–albitization and illitization.
Sulfate concentration, formerly buffered by gypsum-anhydrite deposition, is heavily lowered by bacterial and locally by thermochemical
reduction during burial diagenesis. From an isotopic point of view, data of the water molecule confirm mixing between seawater
and meteoric end-members. Local 18O-shift up to +11‰ at Salsomaggiore is related to water–rock interaction at high temperature (≈150°C) as confirmed by chemical
(Mg, Li, Ca distribution) and isotopic (SO4–H2O) geothermometers. 37Cl/35Cl and 81Br/79Br ratios corroborate the marine origin of the brines and evidence the diffusion of halogens from the deepest and most saline
aquifers toward the surface. The 87Sr/86Sr ratio suggests a Miocene origin of Sr and rule out the hypothesis of a Triassic provenance of the dissolved components
for the analyzed waters issuing from the Emilia-Romagna sector of the foredeep. Waters issuing from the Tuscan side of the
Apennines and from the Marche sector of the foredeep show higher 87Sr/86Sr ratios because of the interaction with siliciclastic rocks. 相似文献
78.
We investigate the bounce cosmology induced by inhomogeneous viscous fluids in FRW space-time (non necessarily flat), taking into account the early-time acceleration after the bounce. Different forms for the scale factor and several examples of fluids will be considered. We also analyze the relation between bounce and finite-time singularities and between the corresponding fluids realizing this scenarios. In the last part of the work, the study is extended to the framework of f(R)-modified gravity, where the modification of gravity may also be considered as an effective (viscous) fluid producing the bounce. 相似文献
79.
Badini Lorenzo Ott Stephan Aondio Patrik Winter Stefan 《Bulletin of Earthquake Engineering》2022,20(11):5963-6006
Bulletin of Earthquake Engineering - In this study a timber-based integrated solution is presented to solve at once common issues affecting typical reinforced concrete (RC) existing buildings, such... 相似文献
80.